As part of the launch of Gmail contextual gadgets, Google released a set of predefined extractors that developers could use. These extractors allow developers to match content within a single part of an email message, such as the subject, and use that content to display relevant information to the current user.

Many Gmail contextual gadget developers have expressed a desire to match on more complex patterns than is possible with the predefined extractors. Today, with the launch of the Google Apps extensions console, these complex patterns, known as custom extractors, are now available to drive contextual gadgets.

Custom extractors allow developers to trigger their gadget when a series of conditions are met. For example, a developer could write an extractor that triggered a gadget only when “Hello world” appeared in the subject and “john@example.com” was the sender of the email. This allows developers to more finely tune their gadgets, and provide even more relevant contextual information.

If you’re interested in writing a custom extractor you can get started by reading our documentation. If you have questions, please post them in the forum.